I can see three benefits for the tools being released:
1. The potential progress is less dependent on your attention/work.
2. There is more visibility for the possibility of doing a translation, assuming the tools were listed in RHDN for example. Otherwise it is mostly up to the visibility of this thread.
3. People may simply be afraid of contacting you, because people are sometimes like that.
That the tools are meant for your personal use/are not very polished/are difficult to use/do not do everything is understandable, and probably a big reason why these kinds of tools aren't often released.
I'll add :
4. It could be an interesting and enlignthning read for romhackers, to see how others work
And I see no real good reason against releasing the code (unless you want to make money with that, which doesn't seem to be the case)
The big reason is that, if I should release the tools, I would have a ton of mails from people asking things such: I can't do XXX, how do I change YYY text?, why don't you program a GUI?... and so on, and frankly, I don't feel like to answer all those mails to people who is not really interested in the making a translation, not even in the game.
So I prefer puting my effort in helping people who is willing to complete a translation, whatever the language.
Noone force you to answer those mails.
I have made some tools to hack Phantasy Star Generations 1 & 2. They are awfully coded (for many reasons), they are not commented, and I think a non-coder user won't be able to make them work. But I'll release them.
I help the persons who use them for the moment (there are 4 persons, a French, an American, a Brazilian and a Spanish - even if the latter never asked anything about it, I wonder where he is
When the work will be done, I'll release the program, I'll let a thread here for bug reports, but I don't even promise I'll fix bugs. After all, the code is free.
But this is your code, you do what you want.